"Sink me if I don't think you're working with them engineers!" he said.

The boys admitted the truth of his statement.

Hawkins' face flushed an angry red and his finger twitched on the rifle's trigger.

"Get off me land 'fore I blast ye off!" he roared.

The boys stepped off the porch and the voice of the parrot screamed after them.

"I'll keelhaul ye! Keelhaul ye! Keelhaul ye!"

Joe looked back and laughed. "Pleasant custom* ersl" he said.

44 They retraced their steps until they were sure Sailor Hawkins could no longer see them, then they headed for the stretch of forest where they had last seen the footprints.

Frank and Joe stopped beside a freshly cut tree stump. In the soft, damp earth around the stump were several footprints which matched the ones they had been following.

"Come on," said Frank. "We'll trail these prints until we find who's at the end of them!"

But the trail ended a few hundred feet deeper in the forest. Whoever had left the footprints had vanished over a stretch of sheer rock-and the prints had vanished with him.

Disappointed, the boys turned back. They had reached the edge of the forest directly above Haw-kins' cabin, when Joe whispered a warning.

Hawkins was sitting on the porch. And sitting with him-talking in urgent tones-was a tall, thin stranger!

CHAPTER VI.

The Missing Scientist.

"wonder who he is?" queried Joe, as he crouched with his brother behind some shrubs at the edge of the woods.

Frank shook his head. "Can you hear what they're saying?" he asked.

Both boys listened intently, but the voices were too far away for them to distinguish the words.

"Maybe we could get closer and hide behind the cabin," Joe suggested.

Frank vetoed the idea. "We couldn't reach the cabin without being seen," he pointed out. "The ground is clear all the way from here to the house."

They strained their ears to catch a few words of the conversation, but to no avail. Finally, the stranger departed.

Frank arid Joe watched him go down the slope.

"I sure wish we could follow him," said Joe, as the man's figure grew smaller and smaller.

"So do I," Frank agreed. "But on the bare hillside he'd be sure to spot us. Come on.

Let's get back to the camp."

It was noon when the boys arrived at Carpenter's camp. From there they could see that Chet had joined Bob and d.i.c.k in the boat. The youth was standing precariously on one of the seats, probing with a long pole at a patch of brambles which clung to the slope a few feet under water.

"Any luck?" Frank called.

"Not yet!" Bob yelled back. "If there's an underground outlet in this valley, we haven't found it!"

"Take it easy, Chet!" Joe called, grinning. "That pole's likely to throw you!"

Chet twisted his head to make a quick retort, and at the same time the pole caught in the brambles. The rowboat shot out from under his feet before he knew what had happened.

For one agonizing instant, Chet dangled helplessly from the end of the pole-then there was a sharp crack as the shaft broke, and he plopped into the water!

Chet rose to the surface, splashing and spluttering. On the sh.o.r.e, Frank and Joe were doubled up with laughter, and Bob and d.i.c.k couldn't help grinning.

Chet looked indignant.

"Don't-see-what's so-funny," he spluttered, his mouth full of water.

"You would, Chet," Joe called back, "if I could only show you a picture of yourself!"

47 d.i.c.k rowed the boat close to the still-spluttering youth, and Bob reached over and pulled him in. As d.i.c.k pulled for the camp, Chet sat dejectedly in the bottom of the boat. He looked a great deal like a s.h.a.ggy, half-drowned dog.

Stepping onto the sh.o.r.e, Chet surveyed himself dismally.

"As if I wasn't hard up for clothes already," he lamented, "this "this had to happen!" had to happen!"

"Never mind, Chet," Frank rea.s.sured him. "I'll drive back to Bayport and bring you a complete new set of duds."

"You will?" Chet said, relieved. "Golly, that'll be swell!"

Bob looked at Frank. "What happened today?" he asked.

"Joe will tell you about it, Bob. I've got to start back to town. See you all later."

Frank started up the hillside toward the ridge. Then, after resting briefly on the mountaintop, he climbed down the outer slope of the mountain to the dirt road where the roadster was parked.

Two hours later, when he mounted the steps of the Hardy front porch, the door was opened for him by his father.

"Dad!" the boy cried. "Gosh, I'm glad to see you! When did you get back? Is your latest case solved?"

Fenton Hardy laughed and slapped his son on the back affectionately.

48 "One question at a time," he said. "Where's Joe?"

Frank started to explain, but there was so much to tell that his words tumbled all over one another. Mr. Hardy led the boy into his study and closed the door.

"Now," he said, "suppose you start at the beginning and describe exactly what has happened."

Frank did so, and Fenton Hardy listened attentively-laughing heartily when his son came to Chet's misadventure in the rowboat.

"That's the whole story, Dad," Frank concluded. And he added gloomily, "So far, we haven't made any progress toward solving any of the mysteries!"

"I wouldn't say that, son," the famous detective replied. "Solving mysteries is pretty much a problem of elimination. The more suspects and clues you can eliminate, the closer you are to the real criminals. It seems to me you're making rather good progress in that direction."

He leaned forward significantly. "The main thing is to find the motive for the crime.

Some person, or group of persons, is causing a water shortage in Bay-port. Why and how?

That's what you've got to find out. When you know the motive, you'll be well on your way to catching the criminal."

"Thanks, Dad," said Frank. "I'll remember that. What about your case? Can you tell me about it?"

Mr. Hardy frowned, then explained that he was 49 working on an a.s.signment for the Ace Laboratories in Pomford, Illinois.

A month ago, Dr. Carl Foster, a scientist-engineer in charge of a secret project at the laboratories, had requested a week's leave of absence. His request had been granted-and the scientist had not been seen since.

The chief of the laboratories was frantic. Dr. Foster had been working on a new process that was expected to revolutionize the building industry, and without him it would be months before the work could continue.

"I questioned everyone at the laboratories, of course," Mr. Hardy went on. "I also went to the hotel where Dr. Foster had been living. The only clue I could find were these sc.r.a.ps of paper."

He took two torn pieces of paper from his wallet and handed them to Frank.

"They're pieces of a telegram," Frank observed.

He studied them carefully. On one of the sc.r.a.ps of yellow paper was a fragment of a typed word: LEN. On the other piece was typed the word BAY.

"Could BAY mean Bayport?" the boy asked.

"It could," his father admitted. "It could also mean Bay Ridge, Bay view, Hudson Bay, and a thousand and one other cities, towns, villages and waterways in North America."

Frank whistled.

"Pomford is a long way from Bayport," Mr. Hardy 50 added, "and so far, I've thought it best to investigate places beginning and ending in BAY which are located in the vicinity of the laboratories." His face clouded. "I must confess that at the moment, Frank, I'm as much up a blind alley as you are!"

Frank grinned. "Maybe we can help each otherl" he suggested.

"Maybe," his father said, smiling. "We've helped each other on cases before!"

There was a knock on the study door. It was Mrs. Hardy, and she expressed surprise at seeing Frank. The youth explained that he had returned to Bayport to obtain some clothes for Chet.

"I guess I'd better hurry out to the Morton farm," Frank said. "Chet will be in a stew until he is wearing his own clothes!"

Mrs. Hardy smiled. "Be sure to give my best wishes to the Mortons," she said. "And, Frank," she called after the retreating boy, "stop at a plumber's shop and ask if he can come out here today and repair a leaking faucet!"

"Tell him it's an emergency!" Aunt Gertrude poked her head into the hall. "We can't afford to waste a drop of water in this town!"

"Okay!" Frank called.

He waved his hand and ran across the lawn to the roadster. A short time later, he was in the business section of Bayport. He scanned a row of store fronts as he guided the car through the heavy traffic. Sud51 denly his eyes were arrested by a sign over one of the shops which read: "J. P. Klenger, Plumber."

Frank swung the roadster into a parking s.p.a.ce in front of the shop and hopped out. A tiny bell tinkled as he opened the shop's door, and a surly-looking man with red hair came from the rear of the store.

He studied Frank unpleasantly as the boy told him of the leaking faucet.

"What do you expect me to do about it?" he said.

Frank stared at him in surprise.

"Fix it," he told the man somewhat heatedly.

The man turned his back on the boy abruptly and started for the rear of the shop.

"Sorry, son," he retorted coolly. "I've got more important things to do."

Frank began to boil. "What's more important for a plumber right now than to help Bayport conserve water until the reservoir is ready?" he demanded.

At the mention of the word "reservoir," the man turned abruptly and shot Frank a queer look.

"Why don't you try another plumbing shop?" he suggested, coming back. "My helper quit because there wasn't enough work. And my bookkeeper left to be married. Someone's got to be here to look after the shop."

In spite of the man's more reasonable tone, Frank .had a feeling there was something back of the plumb52 er's odd behavior. On a sudden inspiration, he thought of his school friend, Gallic Shaw.

"I know a girl who might be willing to take care of your shop," he told the plumber. "She could keep your books, too."

"That so?" Klenger looked interested. He rubbed his chin thoughtfully. "Who is she?" he asked.

"Give me a pencil and a piece of paper," Frank instructed him. "I'll write down her name and address and phone, and you can arrange an interview with her."

Klenger went to a desk littered with account books and papers, and took an office letterhead from one of the drawers. He gave it to Frank, together with a Stubby pencil.

There was much more paper than Frank needed, so he tore off a piece, jotted down Gallic Shaw's name, address and phone number and handed the slip to the man. As Klenger studied it, Frank idly creased the portion of the letterhead which he still held.

The boy's glance fell on the folded paper, and his eyes widened. Dropping his hands below the counter, so Klenger could not see what he was doing, Frank quickly unfolded the sheet. The top of the letterhead read: J. P. Klenger, Plumber. Centered below it was the word: Bayport.

The boy rapidly folded the paper into its former 53 creases. The fragments of two words seemed to leap out at him: LEN BAY.

Frank tried to conceal his excitement. He looked up to find Klenger staring at him. Had the man seen the folded paper?

Klenger soon dispelled the boy's fears.

"Thanks for the tip," he said shortly, holding the sc.r.a.p torn from the letterhead, on which Callie's name was written. "I'll phone the girl right away."

Frank walked casually to the door and went out. But the moment Klenger could no longer see him, he dashed toward the drugstore on the corner.